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A dead humpback whale entered into the port of Ketchikan, Alaska, on the bow of the Princess Cruises "Grand Princess" cruise ship on Wednesday, August 9, 2017.

A cruise ship reached an Alaska port with a surprise on its bow: the carcass of a humpback whale.

The Grand Princess, a 949-foot ship in the Princess Cruises fleet, on Wednesday morning pulled into Ketchikan with the marine mammal lodged on its submerged, bulbous bow, a device designed to avoid wave-making.

Princess spokesman Brian O'Connor said the company was surprised and saddened to discover the whale.

"It is unknown how or when this happened as the ship felt no impact," he said in a statement. "It is also unknown, at this time, whether the whale was alive or already deceased before becoming lodged on the bow."

Navigators, O'Connor said, spotted no whales near the ship as it sailed overnight toward Ketchikan, which is near the southern tip of the Alaska Panhandle just north of British Columbia. Photos indicated that the whale might be a juvenile. The Ketchikan Daily News reported the whale was about 20 feet long.

The ship, with a capacity of 2,600 passengers and a crew of 1,150, was starting its third day of a 10-day round-trip cruise that originated in San Francisco. The Grand Princess was expected to leave Ketchikan later Wednesday.

The cruise line has a comprehensive whale avoidance program, O'Connor said. Ship crews have guidelines on how to operate after spotting whales and alter courses and reduce speed to avoid them.

Ships must not approach within 100 yards (91 meters) of humpback whales and must limit observation time to 30 minutes, O'Connor said. Vessels near humpback whales are required to proceed at a "slow, safe speed" of 10 knots or below, he said.

The National Oceanic and Atmospheric Administration is investigating the incident.

Three distinct populations of humpbacks swim in Alaska waters, said Julie Speegle, NOAA Fisheries spokeswoman. The Western North Pacific population remains endangered. The Mexico population is listed as threatened and the Hawaii population is no longer listed. Whales from the three populations overlap in feeding grounds, Speegle said.

A necropsy was planned to determine the cause of death. Steve Corporon, Ketchikan director of ports and harbors, said a tugboat towed the whale 8 miles (13 kilometers) to Blank Inlet on Gravina Island for the procedure.

It's the second time in two years that a whale has been carried on the bow of a cruise ship into an Alaska port.

An endangered fin whale was spotted on the bulbous bow of Holland America's Zaandam in May 2016 as it prepared to dock in Seward.